CCS | Comprehensive Chromosome Screening

The purpose of Comprehensive Chromosome Screening (CCS) is to analyze, select and transfer only embryos that have the appropriate number of chromosomes. Screening embryos in advance can help achieve higher implantation rates and fewer pregnancy losses, particularly for women 35 or older, couples with multiple-failed IVF cycles or implantation failure, and couples with repeated miscarriages. With CCS, the future of genetic and embryo screening has arrived. RMACT is the only fertility program in the state of Connecticut to offer CCS.

What is Comprehensive Chromosome Screening (CCS)?

Aneuploidy is the term used to describe any embryo with either too many or too few chromosomes. Most people are not aware that aneuploidy is the cause of greater than 60% of miscarriages, as well as the most likely reason that patients do not get pregnant from an in-vitro fertilization (IVF) cycle.

The purpose of CCS is to analyze, select and transfer only embryos that do not have abnormalities in their number of chromosomes. Screening embryos in advance can help achieve higher implantation rates and fewer pregnancy losses, particularly for women 35 or older, couples with multiple-failed IVF cycles or implantation failure, and couples with repeated miscarriages.

The more traditional technique of identifying aneuploidy in IVF embryos was performed with an older technology called fluorescent in situ hybridization (FISH). FISH has many technical drawbacks including the fact that it can only study, at most, 11 chromosome pairs out of all 23 pairs of chromosomes. Therefore 12 or more chromosomes, then, are not examined, resulting in only partially screened embryos which can lead to miscarriages or infants born with chromosomal disorders. Additionally, FISH requires removal of only a single cell on day 3 of development. This greatly decreases the accuracy of the testing and may even harm the embryo as there are only 6-10 cells at that stage of development. In fact, several well-regarded research studies have shown that using FISH on day 3 embryo does not improve outcomes over traditional IVF.

Conversely, during CCS, we obtain 5-10 cells on a day 5 or 6 embryo called a blastocyst. Biopsying the embryo at a more advanced cell stage dramatically increases the accuracy of this testing and minimizes potential damage that the biopsy can cause on the embryo because it has several hundred cells by then.

Another advantage to CCS is that we can greatly reduce the odds of a couple having multiple pregnancies (twins or triplets). It arms clinicians with the knowledge that they are transferring the most chromosomally fit embryo, therefore precluding the need to transfer multiple, unscreened embryos in the hope that one will be healthy enough to create an ongoing pregnancy and a healthy baby.

Embryo Screening

The new analytical technology involves quantitative real-time polymerase chain reaction (qPCR) and allows for the evaluation of all 23 pairs of human chromosomes from several embryonic cells. The ability to determine this chromosomal information with such a high rate of precision in a fresh embryo transfer is available at only a few centers across the entire country.

Comprehensive chromosome screening (CCS) is the future of embryo screening and is a proprietary patent pending technology.

The application of qPCR won the general prize paper at the 2010 American Society for Reproductive Medicine (www.ASRM.org) meeting as the first prospective, randomized trial to demonstrate a significant improvement in ongoing pregnancy rates using aneuploidy screening. This is the highest research honor in reproductive medicine in the United States and highlights the acceptance of our procedures for CCS by the national professional societies.

Participate in Additional Studies

We are currently recruiting patients for additional studies to continue to share this data in peer-reviewed medical journals. The three (3) studies being recruited for are:

1. The Impact of Vitrification on Oocytes: More information is available here.

2. The Study of the Efficacy of 24 Chromosome Preimplantation Genetic Diagnosis (PGD): More information is available at www.clinicaltrials.gov/PGD

3. The Evaluation of the Impact of Embryo Biopsy on the Reproductive Potential of Embryos Undergoing In-Vitro Fertilization: More information is available here.

For our patients to participate in either of these studies they would have monitoring in our CT offices. RMA of Connecticut patients interested in study participation should contact their nurse to see if they are candidates.

CCS is not a perfect science and does have inherent false positive and negative rates due to the limited number of cells available for testing and embryo mosaicism. Based on current data the error rate is less than 1%, but as with any technology we recommend that patients err on the side of caution. If a pregnancy is established, traditional prenatal diagnosis like chorionic villus sampling or amniocentesis is highly recommended.

The utilization of CCS is particularly important for patients over 35 as they are more prone to chromosomal errors in their eggs due to the “biological clock”, as well as those patients with a history of many miscarriages, termed Recurrent Pregnancy Loss (RPL). This technology provides the ability to prescreen embryos for chromosomal errors such as Down’s syndrome and other similar aneuploidy conditions.

The above are clinical studies, but RMACT believes Comprehensive Chromosome Screening (CCS) is a promising and beneficial procedure for all patients seeking to increase their chances of implantation and decrease the chances of a miscarriage. Previous studies, published in leading medical journals and presented at the national meetings of ASRM have shown the safety and efficiacy of CCS. The current studies serve to enlarge this database further and share it with the scientific community at-large. We are delighted to announce ongoing healthy babies born from this approach.

It is our hope that by offering this dramatic medical improvement we will be able to help more families have the children they desire in a safer and more efficient manner.

For more information about CCS, or to speak with one of our board-certified Reproductive Endocrinologists and infertility specialists, please contact us. We’re here to help.